RESULTS AND DISCUSSIONS
4.6. Circumference
Circumference or core diameter of lettuce canopy had significantly varied due to different growing medium (Figure 12).The highest circumference (37.84 cm) was calculated for P1 and P2 at 20 DAS. P1 (48.59 cm) was responsible for the highest lettuce canopy at 30 DAS. Statistical similarity was found between P1 (52.95 cm) and P2 (53.31 cm) at 40 DAS and P2 (56.76 cm) and P1 (54.53 cm) at 50 DAS.
Elgubshawi and Attia (2019) concluded that Leaf area index, Avg. core length and yield (marketable yield) were significantly responded to relatively higher amounts of organic manures (24t/acre) in a sand soil.
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Varieties influenced circumference at 30, 40 and 50 DAS, however, it did not generated significant variation at 20 DAS (Figure 12). The higher value was always recorded from V1 (35.35 cm, 40.74 cm, 47.57cm and 51.32 cm) in comparison with V2 (32.91cm, 38.60cm, 45.49cm and 48.93 cm).
Circumference of lettuce was significantly varied due to interactive effect of growth medium on two lettuce varieties (Table 6). While longest circumference at 20 DAS and 30 DAS was found for V1P1 (38.07 cm and 49.46 cm , respectively), it was obtained from V1P2 at 40 DAS (56.76 cm) and 50 DAS (59.97 cm). The shortest circumference was recorded for V2P0 at 20, 30, 40 and 50 DAS (25.04 cm, 26.61cm, 37.84cm and 42.78 cm , respectively).
Figure 12. Effect of Growth Media on Circumference of Canopy
Here, P0 Control, P1 SVC, P2 SV, P3 SVS; DAS Days after Sowing;
Vertical bars represent error
20DAS 30DAS 40DAS 50DAS
Circumference of canopy (cm) P0 P1 P2 P3
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Figure 13. Effect of Varieties on Circumference of Lettuce
Here, V1 Green Wave and V2 New Red Fire; DAS Days after Sowing;
Vertical bars represent error
Table 6. Interaction effect of Growth Medias on Circumference of Two Lettuce Varieties at Different Days After Sowing (DAS)
Treatment Combination Circumference (cm)
20 30 40 50
V1P0 30.72b 31.95d 37.92d 44.75 c
V1P1 38.07a 49.46a 53.40ab 55.15 b
V1P2 37.68a 44.98 b 56.76a 59.97a
V1P3 34.93ab 36.58 c 42.23c 45.40 c
V2P0 25.04c 26.61e 37.84d 42.78 c
V2P1 37.60a 47.73ab 52.50 b 53.90 b
V2P2 37.99a 43.88 b 49.86b 53.55 b
V2P3 31.01b 36.19 cd 41.75 c 45.50 c
LSD (0.05 ) 4.46 4.43 3.71 3.76
Here, V1 Green Wave and V2 New Red Fire; P0 Control, P1 SVC, P2
SV, P3 SVS;
Means in same column with different letter(s) are significant at 0.05 level of probability.
20DAS 30DAS 40DAS 50DAS
Circumference of canopy (cm) V1 V2
43 4.7. Yield parameters
4.7. 1. Fresh weight per plant
Significant varietal variation was calculated on fresh weight of each plant at harvest (Table 7). V1 generated significantly heavier plants (126.8 g) than V2 (120.69g).
Tsiakaras et al. (2014) reported that cultivars had significant effect on fresh weights of individual plants.
Fresh weight of per lettuce plant exhibited significant differences due to influence of various organic growing medium at harvest (Table 7). The healthiest plant (134.63 g) was recorded for P1. The least heavy plant was observed for P0 (113.19 g).
Combined effect of variety and growing media produced a statistically significant variance on fresh weight of plant at harvest (Table 7). The weight of the healthiest plants at harvest was noted for V1P1 (141.75 g). The least heavy plant at fresh condition was detected at V2P0 (112.00g) which was statistically similar to V1P0
(114.37 g).
4.7.2. Dry weight per plant
Varieties significantly altered the dry weight of individual lettuce plant (Table 7). V1
(14.53g) significantly outperformed the dry mass of individual plant recorded from V2 (13.08g).
The individual dry weight of plant was significantly varied with a variation in growth medias (Table 7). The highest and lowest dry weight was obtained from P1 (16.71 g) and P0 (11.19 g), respectively. Masarirambi et al. (2012) concluded that lettuce provided with 60 t/ha of vermicompost exhibited higher values in individual plant dry mass.
Interacting effect of variety and growth medias had a significantly variable influence on individual plant dry mass (Table 7). The greatest dry mass per plant was noted for V1P1 (17.65 g). The plant with least dry mass was detected under V2P0 (10.19g).
44 4.7.3. Individual of yield growth device
Varieties influenced individual yield per growth device significantly (Table 7). The higher value was recorded from V1 (0.63 kg) in comparison with V2 (0.60 kg).
Individual growth device yield of lettuce was significantly varied due to different organic manures (Table 7). The highest yield (0.67 g) was measured for P1 and P0 (0.57 g) was responsible for the lowest yield per growth device. Elgubshawi and Attia (2019) concluded that Leaf yield per plot (marketable yield) was significantly responded to relatively higher amounts of organic manures (24t/acre) in a sand soil.
Yield of lettuce from individual growth device was significantly varied due to interactive effect of organic manure on two lettuce varieties (Table 7). While V1P1 produced the highest yield (0.71 g), V2P0 was the least yield (0.56 g) producing combination.
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Table 7. Effect of Growth Medias, Varieties and Interaction of Growth Medias And Varieties on Yield Contributing Characteristics and Yield of Lettuce
Yield Parameters Fresh Weight
per Plant (g)
Dry Weight per Plant
(g)
Yield per device
(kg) Variety
V1 126.38a 14.53a 0.63a
V2 120.69b 13.08b 0.60 b
LSD ( 0.05) 1.61 0.69 0.008
Organic Manure
P0 113.19d 11.19d 0.57 d
P1 134.63a 16.71a 0.67a
P2 124.44b 14.18b 0.62b
P3 121.88 c 13.14c 0.61c
LSD (0.05) 2.28 0.98 0.01
Treatment Combination
V1P0 114.37 d 11.48de 0.57d
V1P1 141.75 a 17.65a 0.71a
V1P2 127.62 b 15.90b 0.62b
V1P3 121.75 c 13.08c 0.61c
V2P0 112.00 d 10.90e 0.56d
V2P1 127.50 b 15.78b 0.64b
V2P2 121.25 c 12.45cd 0.61c
V2P3 122.00 c 13.20c 0.61c
LSD (0.05) 3.23 1.37 0.02
Here, V1 Green Wave and V2 New Red Fire; P0 Control, P1 SVC, P2
SV, P3 SVS;
Means in same column with different letter(s) are significant at 0.05level of probability.
46 4.8. Organoleptic test
Marketable parameters such as- crispness, sweetness, bitterness, sourness and appearance of lettuce leaf influence its acceptability to consumer. These qualitative parameters were analyzed by organoleptic test. A 25 member judge panel was created from of the students of Sher-e-Bangla Agricultural University, Dhaka.
Samples of lettuce from different treatment combinations alone with a questionnaire (Appendix XV) were served among the judges in order to evaluate its acceptability.
The results of test were summarized in Table 8. The findings revealed that lettuce grown with V2P1 treatment combination had the highest marketable quality with a score 3170. In contrast, the lowest score (2974) was recorded in the treatment combination of V2P3.
V2P1 secured the top score (684) among the different treatment combination in terms of crispiness. The lowest scoring treatment combination was V1P3 (568). In respect of sweetness, produce from V2P1 obtained the highest score (660), whereas the lowest score was recorded for V1P2 (560). Plants from V2P3 and V2P1 treatment combination the highest score (632) and lowest score (592), respectively, in case of bitterness. Produce from V1P1 (612) obtained the highest sourness acceptance, while produce from V2P3 (540) had least acceptability based on sourness. The highest appearance score (632) was obtained by leaves from V2P1 treatment combination, whereas the least desirable appearance was found from V1P0 (584).
A prediction of the consumers‟ likings on different marketable qualities of the produced lettuce can be make based on the present results.
47 Table 8. Quality Attributes of Lettuce
Crispness Sweetness Bitterness Sourness Appearance Total
V1P0 604 592 612 600 584 2992
V1P1 632 580 604 612 604 3032
V1P2 620 560 620 598 602 3000
V1P3 568 632 620 604 592 3016
V2P0 580 604 624 564 604 2976
V2P1 684 660 592 602 632 3170
V2P2 656 572 598 578 604 3008
V2P3 592 608 632 540 602 2974
Organoleptic test was done by following formula of Villared et al. (1979)
Here, V1 Green Wave and V2 New Red Fire; P0 Control, P1 SVC, P2
SV, P3 SVS;
Highly Acceptable (HA=7), Slightly Acceptable (SA=5) and Not acceptable (NA=2) 4.9. Safety test
Samples of lettuce leaf from every treatment combination were tested at Molecular and Environmental Microbiology Laboratory, BRAC University. The test was undertaken to detect and enumerate the presence of bacterial population in organically grown lettuce and the results were expressed in terms of Colony Forming Units per Gram (CFU/g). The results of the test are summarized and presented in Table 9.
In general, V1P0, V2P1 and V2P2 had greater amount of bacterial infestation, whereas, V2P0 has exhibited the least amount of infestation. E. coli was present in all the samples. Highest CFU/g was recorded from V2P1 (3810) and the lowest count was found for V2P0 (120). The CFU/g for Klebsiella spp. ranged from 210(V2P0) to 4950 (V2P2). The highest and lowest CFU/g for Enterococci spp. was found in V2P2 (3750) and V2P0 (120), respectively. The colony forming unit in each gram of lettuce for Bacillus ssp. varied from 1920 (V1P2) to 360 (V2P0). Salmonella spp. were absent from all samples. Heterotopic Plate Count (HPC) was greater than 9000 in all treatment combinations. The range of Total Coliform (TC) was 8250 (V2P1) – 450 (V2P0).
Fowler and Foster (1976) reported that green salad (fresh lettuce leaf) from an arm- forced medical facility had a Total Plate Count (TPC) range of 3.0 x 103 -3 x107/g,
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with a mean of 1.9 x 107/g and the salad was safe for consumption. Usually, food that are consumed at fresh condition, such as- fruits and salad crops contain a large number of bacterial population as part of their natural micro-flora. Aerobic colony count (ACC) or HPC or standard plate count provides valuable information on the general quality and remaining shelf life of the food as a quality indicator; however, it cannot be assisted directly as safety assessment of food (Anon., 2014).
Table 9. Colony Forming Units per gram (CFU/g) of Lettuce Leaf under Different treatment combinations
E.
coli
Klebsiella spp.
Enterococci Bacillus spp.
Salmonella spp.
HPC TC
V1P0 2220 1740 1650 870 Absent >9000 5100
V2P0 120 210 120 360 Absent >9000 450
V1P1 960 630 570 1080 Absent >9000 4560
V2P1 3810 1050 3330 540 Absent >9000 8250
V1P2 360 300 150 1920 Absent >9000 1110
V2P2 3480 4950 3750 810 Absent >9000 7950
V1P3 1080 990 510 1890 Absent >9000 2400
V2P3 390 600 420 1020 Absent >9000 1350
Here, V1 Green Wave and V2 New Red Fire; P0 Control, P1 SVC, P2
SV, P3 SVS;
HPC: Total Heterotopic Count; TC: Total Coliform